Image forming apparatuses such as laser beam printers are well known. Such image forming apparatuses include, for example, an image bearing member for bearing a latent image, and a developing device for developing the latent image borne on the image bearing member with a developer, wherein the developing device can be mounted to and dismounted from a mounting and dismounting section provided in the image forming apparatus main unit. When an image signal or the like is sent from an external device, such as a host computer, to this image forming apparatus, the developing device is positioned at the developing position opposite to the image bearing member, a developer image is formed by developing the latent image borne on the image bearing member with the developer inside the developing device, and an image is ultimately formed on the medium by transferring this developer image onto the medium.
Such a developing device has a positioning member for positioning a developing device main unit with respect to the mounting and dismounting section by engaging with the mounting and dismounting section when being mounted to the mounting and dismounting section. This positioning member is fixed to one end, with respect to the longitudinal direction, of the developing device main unit. Moreover, the developing device includes an element that can communicate in a noncontacting manner with the image forming apparatus main unit side when the developing device is mounted to the mounting and dismounting section.
Furthermore, there are developing devices that have a coupling member that is attached to the other end, in longitudinal direction, of the developing device main unit and that is coupled to the mounting and dismounting section when the developing device is mounted to the mounting and dismounting section. This coupling member is attached in such a manner that its relative position to the developing device main unit can be changed, for the purpose of setting the spacing between the image bearing member and the developing device when the developing device develops the latent image borne on the image bearing member to a desired spacing, even when the image bearing member is attached in a slanted manner with respect to the image forming apparatus main unit (see publication of WO 03/098355).
Now, in this developing device, the coupling member that is coupled to the mounting and dismounting section when the developing device is mounted to the mounting and dismounting section is attached to the developing device main unit in such a manner that its relative position to the developing device main unit is variable, so that depending on the position where the element is attached to the developing device main unit, there is the possibility that the distance between the element and the image forming apparatus main unit changes considerably as this relative position changes. In this case, there is the risk that the element cannot communicate properly with the image forming apparatus main unit side.
Also, image forming apparatuses that make recordings by electrophotography, in which an electrostatic latent image on the surface of a carrying member fabricated by a photoconductor is exposed and formed, are known, and in such image forming apparatuses, the toner image on the surface of the carrying member, obtained by developing this electrostatic latent image with toner, is transferred to a recording medium, such as recording paper, to accomplish image formation. This toner image is developed with toner by rotating a developing roller facing the surface of the carrying member and letting toner on the outer circumferential surface of that roller selectively transfer to the electrostatic latent image on the surface of the carrying member and adhere to it.
Among such image forming apparatuses employing recording by electrophotography, there are also apparatuses configured such that developing cartridges (developing containers), which include not only the developing roller facing the carrying member but also a container containing the toner, can be mounted removably, and a plurality of such developing cartridges can be accommodated in a developing rotary unit. In such an image forming apparatus, the developing cartridge at the developing position in which the developing roller faces the carrying member can be switched by rotating this developing rotary unit around a rotation shaft.
Thus, by devising such an image forming apparatus such that developing cartridges containing yellow (Y), magenta (M), cyan (C) and black (K) toner, respectively, serving as the developing cartridges adhering toner to the carrying member surface can be accommodated by (mounted to) the developing rotary unit, it is possible to form a color image in which toner of various colors is superimposed on each other by successively switching the developing cartridges. Needless to say, with this configuration, it is also possible to form a single-color image with toner of one color, for example a black-and-white monochrome image (referred to simply as monochrome image in the following) obtained with black (K) toner.
Here, in such an image forming apparatus, toner development is performed while both the carrying member and the developing roller rotate, so that it is difficult to transfer all of the toner on the circumferential surface of the developing roller to the carrying member or recover it inside the developing cartridge. Therefore, since the toner is a fine powder, it may scatter/drift from the developing position facing the carrying member to the surroundings and accumulate, and that it pollutes the recording paper or the like. For this reason, there are cases in which image forming apparatuses employing electrophotography are provided with an exhaust duct that provides suction in the vicinity of this developing position and exhausts.
Moreover, with an image forming apparatus provided with such a developing rotary unit, it is possible to freely choose, for example, the toner color of each of a plurality of the developing cartridges individually, and since also the remaining toner amount differs, it has been proposed to place a memory (storage element) storing and holding various kinds of information on each developing cartridge (see for example Patent Document 1). In this case, by accessing the memories in the developing cartridges, it is possible to confirm the type of the developing cartridge by reading out the information in the memory, and to associate various kinds of information with the developing cartridges themselves, by rewriting for example the remaining amount of toner contained in them (see WO 03/098356).
However, in such image forming apparatuses, devices generating heat, such as a device exposing/forming the electrostatic latent image on the carrying member surface or the fixing device that fixes the toner image by applying pressure and heat to the recording paper onto which the toner image has been transferred, are arranged inside the apparatus main unit. Therefore, when the memories placed on the developing cartridges are subjected to this thermal influence, then there is the risk that the storage elements placed on the developing cartridges of this image forming apparatus are not only adversely affected, but in the worst case errors may occur during the reading and writing (rewriting) of storage information in those memories.
Furthermore, if the stored information is read out and written by communication in a noncontacting manner with the memories of the developing cartridges from the apparatus main unit side, then there is similarly not only the risk that a communication controller is adversely affected by the heat inside the apparatus main unit, but also that, in the worst case, the communication performance drops.
Moreover, it is necessary to establish a connection, to the memories on the outer surface of the rotating developing cartridges accommodated in the developing rotary unit, that allows the exchange of various kinds of information (signals).
On the other hand, as shown in FIG. 30(a), in this image forming apparatus, a suction opening 2161a of an exhaust duct 2160 provides suction near a developing position where a developing roller 2014a of a developing cartridge 2014 faces a carrying member 2012, but as shown in FIG. 30(b), there may be a case where the rotation of a developing rotary unit 2015 for switching the developing cartridge 2014 begins before all of the drifting toner t is sucked away, and the drifting toner t moves along the outer surface of the developing cartridge 2014 before it is sucked away. This problem becomes more significant the more the processing speed of the image formation increases, since the time for which the developing cartridge 2014 stops after the developing is finished becomes shorter.
Typically, a memory 2141 placed on the outer surface of this developing cartridge 2014 is placed in the middle with respect to the main scanning direction (the axial direction of the developing roller 2014a), as described in the above-noted Document 1. Moreover, the suction opening 2161 of the exhaust duct 2160 is formed such that it covers the entire axial length of the developing roller 2014a facing the carrying member 2012, so as to suck in the drifting toner t. Therefore, the memory 2141 on the outer surface of the developing cartridge 2014 is moved within a region where it comes into contact with the drifting toner t (the region where it passes near the suction opening 2161).
However, if the communication section communicating with the apparatus main unit side in order to exchange storage information inside the memory 2141 on the side of the developing cartridge 2014 is polluted through contact with drifting toner t, there is the risk of communication faults, regardless of whether this communication section is connected in a contacting manner or in a noncontacting manner. When accessing the memory 2141 in such a state of connection fault, there is the risk that errors occur in the reading or writing (rewriting) of the information stored in the memory 2141. Moreover, when the surface of the memory 2141 is polluted, then there is the possibility that for example the outer surface of the memory 2141 is adversely affected by adhering substances.
Moreover, devices generating heat during operation (heat sources) are placed inside the apparatus main unit, for example an exposing unit that forms the electrostatic latent image by exposing/scanning the carrying member surface is disposed in a lower part of the apparatus main unit. In the course of the faster speeds attained in recent years, the amount of heat generated by the exposing unit, which is a heat-generating member, has increased, and in the course of miniaturization the various parts of the apparatus are laid out at ever closer positions.
Therefore, if the developing cartridge is laid out such that it rotates at a position close to the exposing unit, then it may stop its rotation at a position facing this exposing unit. In this situation, when for example the memory on the outer surface of the developing cartridge or the communication controller is subjected to the thermal influence of the exposing unit, whose temperature has increased, then it is at least adversely affected, and in the worst case, there is the risk that errors may occur in the reading and writing (rewriting) of information stored in this memory, and the communication performance drops.
Also, image forming apparatuses that make recordings by electrophotography, in which an electrostatic latent image on the surface of a carrying member fabricated by a photoconductor is exposed and formed, are known, and in such image forming apparatuses, the toner image on the surface of the carrying member, obtained by developing this electrostatic latent image with toner, is transferred to a recording medium, such as recording paper, to accomplish image formation. This toner image is developed with toner by rotating a developing roller facing the surface of the carrying member and letting toner on the outer circumferential surface of that roller selectively transfer to the electrostatic latent image on the surface of the carrying member and adhere to it.
In such image forming apparatuses employing electrophotography, there are also apparatuses configured such that developing cartridges (developing containers), which include not only the developing roller facing the carrying member but also a container containing the toner, can be mounted removably, and a plurality of such developing cartridges can be accommodated in a developing rotary unit. In such an image forming apparatus, the developing cartridge at the developing position in which the developing roller faces the carrying member can be switched by rotating this developing rotary unit around a rotation shaft.
Thus, by devising such an image forming apparatus such that developing cartridges containing yellow (Y), magenta (M), cyan (C) and black (K) toner, respectively, serving as the developing cartridges adhering toner to the carrying member surface can be accommodated by (mounted to) the developing rotary unit, it is possible to form a color image in which toner of various colors is superimposed on each other by successively switching the developing cartridges. Needless to say, with this configuration, it is also possible to form a single-color image with toner of one color, for example a black-and-white monochrome image (referred to simply as monochrome image in the following) obtained with black (K) toner.
Moreover, with image forming apparatuses including such a developing rotary unit, it is possible to freely select for example the toner color of each of a plurality of the cartridges individually, and since also the remaining toner amount differs, it has been proposed to place a memory (storage element) storing and holding various kinds of information on each developing cartridge, and use the memory to read or write information stored in the memory by communication in a noncontacting manner via antennas (see publication of WO 03/098356). In this case, by accessing the memories in the developing cartridges, it is possible to confirm the type of the developing cartridge by reading out the information in the memories, and to associate various kinds of information with the developing cartridges themselves, by rewriting for example the remaining amount of toner contained in them.
However, in such conventional image forming apparatuses using recording by electrophotography, the toner is transferred using a potential difference, when developing the electrostatic latent image formed on the surface of the carrying member by adhering toner to it. Therefore, in this image forming apparatus, it is necessary to charge one or both of the members passing on or receiving the toner to a high voltage, and there is the possibility that noise is emitted during the charging or from the charged member. Therefore, when this noise unnecessarily enters for example an antenna performing communication in a noncontacting manner to rewrite the information stored in the memory placed on the developing cartridge, then there is the risk that the information stored in the memory is deleted or otherwise becomes inaccurate.
Moreover, image forming apparatuses such as laser beam printers are well known. Such image forming apparatus include, for example, a photoconductor for carrying a latent image, and a developing device that develops the latent image borne on the photoconductor by the developer and that can be mounted or dismounted with respect to the image forming apparatus main unit. When image signals or the like are sent from an external device, such as a host computer, the developing device is positioned in the developing position at which it faces the photoconductor, the latent image borne on the photoconductor is turned into a developer image by developing it with the developer inside the developing device, this developer image is transferred onto a medium, and finally an image is formed on the medium.
Moreover, there are developing devices including an element that can perform wireless communication with an antenna with which the image forming apparatus main unit is provided, facing that antenna across a gap in a state in which the developing device is mounted to the image forming apparatus main unit (see publication of WO 03/087952).
Now, when the element and the antenna perform wireless communication, electromagnetic waves are propagated through the gap between the element and the antenna. Therefore, when too much noise intrudes into this gap from the outside, suitable wireless communication is obstructed. Consequently, there is a need for a way to reduce the amount of noise intruding into that gap.
Moreover, as a cartridge mounted to a laser beam printer or the like serving as an image forming apparatus, a developing device containing a developer is known, for example. This developing device is provided with a memory unit for storing a toner consumption amount or a remaining toner amount, for example. This memory unit includes an IC memory and an antenna for communicating contactlessly with the printer main unit in a position in which it faces that antenna, which is provided on the main unit side, when the developing device is mounted to the printer main unit (see WO 03/098356). Moreover, in order to ensure favorable communication conditions between the memory unit and a communication unit, the memory unit is provided at an outer circumference of the cartridge, so as to come close to the communication unit.
Now, the developing device is mounted in the printer by passing it from outside the printer through a frame of the printer or the like. Since the frame of the printer needs to ensure rigidity and prevent the intrusion of light to the region near the photoconductive drum, also the opening for mounting the developing containers is formed slightly larger than the outer shape of the process cartridges. Therefore, when a developing device is held by a user or the like and mounted to the printer, the developing device is in an instable state until a portion of the developing device is supported by the printer, and there is the risk that the IC memory of the memory unit provided on the outer circumference of the developing device is damaged by inadvertently bumping it into the frame of the printer or the like. Therefore, there was the problem that the user, for example, has to insert the developing device carefully into the printer.
Moreover, as a cartridge mounted to a laser beam printer or the like serving as an image forming apparatus, a process cartridge provided with a photoconductive drum or a developing roller is known, for example. This process cartridge is provided with a memory unit for storing the time that the photoconductive drum has been used, for example. This memory unit includes an IC memory and an antenna for communicating contactlessly in a position in which it faces a communication unit provided on the main unit side when the process cartridge is mounted to the printer main unit (see JP-A-H11-348375).
In such an image forming apparatus, there is the problem that favorable communication is not possible when the memory unit and the communication unit are not arranged at suitable positions, in order to perform communication in a noncontacting manner between the memory unit and the communication unit.
Moreover, for example, a developing device mounted to a laser beam printer or the like is known as a developing device containing a developer. This developing container is provided with a memory unit for storing a toner consumption amount or a remaining toner amount, for example. This memory unit includes an IC memory and an antenna for communicating contactlessly with the printer main unit by electromagnetic induction, in a position in which it faces an antenna provided on the main unit side when the developing container is mounted to the printer main unit (see publication of WO 03/087952). Moreover, in order to ensure favorable communication conditions between the memory unit and a communication unit, the memory unit is provided at an outer circumference of the developing device containing the developer, so that the memory unit comes close to the communication unit.
As the developer used in the laser beam printer, there are developers in which a magnetic material, that is, a material having conductivity, is included, as in developers in which for example a non-magnetic toner and a magnetic carrier are mixed together. When such a developer including a magnetic material is contained inside the developing container, then there is a case where it contacts the inner circumferential surface at a position where the memory unit is provided on the outer circumference side, so that the magnetic material is contained there and the magnetic material adheres to this inner circumferential surface.
However, since the memory unit and the communication unit communicate by electromagnetic induction, when a magnetic material is present at the inner circumferential surface of the developing container where the memory unit is attached, then there is the problem that when the magnetic flux generated on one side passes through the magnetic material, eddy currents flow in the magnetic material with the magnetic flux at the axial center, the propagated waves are attenuated considerably, and communication may not be possible.
Moreover, as a cartridge mounted to a laser beam printer or the like serving as an image forming apparatus, process cartridges provided with a photoconductive drum or a developing roller are known, for example. Such a process cartridge is provided with a memory unit for storing the time that the photoconductive drum has been used, for example. This memory unit includes an element and an antenna for communicating contactlessly in a position in which it faces the communication antenna, which is provided on the printer side, when the process cartridge is mounted inside the printer (see JP-A-H11-348375).
In such an image forming apparatus, the outer circumference is covered by a cover or the like, and the temperature inside the apparatus increases due to heat generated by electric components during the image forming operation. At this time, also the temperature of the antenna for communication, which is provided on the printer side, may increase. In the above-described case, in which the memory unit communicates contactlessly with the printer, there is the problem that, depending on the antenna characteristics, there is the risk that favorable communication between the memory unit and the printer may not be possible when the temperature of the antenna provided on the printer side increases.
Moreover, image forming apparatuses such as laser beam printers are already well known. Such image forming apparatus include, for example, a photoconductor for carrying a latent image, and a developing unit that develops the latent image borne on the photoconductor with a developer and that can be mounted or dismounted with respect to the image forming apparatus main unit. When image signals or the like are sent from an external device, such as a host computer, the developing unit is positioned in the developing position at which it faces the photoconductor, the latent image borne on the photoconductor is turned into a developer image by developing it with the developer inside the developing unit, this developer image is transferred onto a medium, and finally an image is formed on the medium.
Moreover, among such developing units, there are developing units that have a memory unit including a memory, and onto which a label on which information relating to the developing unit is written is stuck (see publication of WO 03/098356).
Moreover, in determining where to attach the memory unit to the developing unit, the prevention of damage to the memory unit needs to be taken into consideration. Since the developing unit is mounted and dismounted by a user or the like, it is necessary to devise measures effectively preventing damage to the memory unit by the user touching the memory unit or the memory unit touching other parts of the image forming apparatus during the mounting or dismounting.
As an approach to solve this problem, the approach of embedding the memory unit in the developing unit and covering it with a lid is known. However in this case, it is necessary to provide a separate lid, so that the number of parts increases.